JP3406412B2 - Image capture device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image of an object pattern when assembling, processing or inspecting an electronic device (a substrate such as a semiconductor wafer or a printed wiring board or a display device such as a CRT or LCD). The present invention relates to an image capturing device for capturing.

[0002]

2. Description of the Related Art Conventionally, assembling and processing electronic devices,
In order to capture an image of a target pattern on a large screen when performing an inspection or the like, the target is placed on a movable stage, and the movable stage is moved to switch the field of view for capturing an image. Was used.

As another conventional image capturing device,
For example, some of them have been disclosed in JP-A-61-39539. That is, it is an image capturing device that inspects the object pattern by switching the field of view for capturing the image of the object pattern by the swing mirror.

FIG. 9 is a block diagram showing the structure of a conventional image capturing device. In the figure, 1 is a standard object having a defined correct pattern, 2 is an inspected object positioned at an accurate position with respect to the standard object 1, and 3 is a standard object 1 and an inspected object 2. The oscillating mirror is arranged so as to oppose to. The swing mirror 3 swings back and forth to change the tilt angle, and alternately switches the optical axis 1a of the incident light from the standard object 1 and the optical axis 2a of the incident light from the inspection object 2, It is formed so as to be able to reflect along a predetermined optical axis 4. A lens means 5 is arranged on the optical axis 4 and collects the reflected light of the swing mirror 3 to form an image at a predetermined position.
Reference numeral 6 denotes an optical sensitive means such as a TV camera provided with an image sensor which is placed at the image forming point of the lens means 5 and can convert the presence or absence of light into an electric signal and output the electric signal. Reference numeral 7 denotes a gate circuit for passing an output signal from the optical sensitive means 6 in synchronism with the switching of the oscillating mirror 3, a differentiation circuit and a filter for extracting a variation from the output signal of the gate circuit, and a differentiation circuit thereof. And 8 is a display unit for displaying an object pattern image or the like as the output of the processing unit 7.

Next, the operation will be described. The oscillating mirror 3 is oscillated at a predetermined switching frequency, and the images of the standard object 1 and the object 2 to be inspected are alternately switched, and the optical sensitive means 6 is provided.
Lead to. If there is no defect in the pattern of the inspection object 2,
The output signal from the optical sensitive means 6 is only the DC component, but if there is a defect in the pattern, the change becomes an AC component signal corresponding to the switching frequency and is taken out by the differentiating circuit of the processing unit 7.

[0006]

Since the conventional image capturing device is constructed as described above, the image capturing device having the movable stage has a problem that it takes time to move the stage. . In addition, JP-A-61-395
In the image capturing device as disclosed in Japanese Patent Publication No. 39, the optical axes on which the lens means 5 is focused are only the optical axis 1a and the optical axis 2a, and only the image of two predetermined places can be captured. However, there is a problem in that it takes time to process an image of the entire surface of an object pattern on a large screen.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce the size of the entire apparatus by eliminating the need for a movable stage. An object is to obtain an image capturing device capable of capturing an image of the entire surface of an object pattern at high speed and with high accuracy.

Another object of the present invention is to provide an image capturing device capable of capturing a highly accurate object pattern image at high speed.

[0009]

According to a first aspect of the present invention, there is provided an image capturing device comprising: first lens means; and optical axis deflection switching means for deflecting the optical axis passing through the first lens means and switching the optical axis at a predetermined frequency. An optical sensitive means which is responsive to an optical image passing through the optical axis deflection switching means and outputs a predetermined video signal; and the optical sensor which is arranged between the optical axis deflection switching means and the optical sensitive means. Second lens means for guiding an optical image passing through the axial deflection switching means to the optical sensitive means, and a processing unit for processing the video signal output from the optical sensitive means to obtain an image of the object. The distance between the first lens means and the center of the object is DST.
When the focal length of the first lens means is f1 and the object has a high convex shape in the center, DST is set to 0.
0> f1, DST0 <f1 when the object has a low central concave shape, and DST when the object has a constant height.
This is formed so that ST0 = f1 can be set.

An image capturing device according to the invention of claim 2 is
A control unit for adding the value determined by the mathematical formula and the correction table value created from the measurement data and controlling the optical axis deflection switching means to perform visual field positioning is provided.

[0011]

According to the first aspect of the present invention, in the image capturing apparatus, the optical axis passing through the first lens means is deflected by the optical axis deflection switching means and switched at a predetermined frequency, and then guided to the optical sensitive means by the second lens means. Then, the video signal output from the optical sensitive means is processed by the processing unit,
Even for a large-area object whose height is not constant, an image of the entire surface of the object pattern can be captured at high speed and with high accuracy.

In the image capturing device according to the second aspect of the present invention, the visual field is roughly positioned by a value determined by a mathematical expression, and an error peculiar to the device is corrected by a correction table value created from measurement data to switch the optical axis deflection. By controlling the means, a more accurate object pattern image is captured.

[0013]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. Figure 1
FIG. 9 is a block diagram showing an image capturing device according to an embodiment of the present invention, in which the corresponding parts shown in FIG. In the figure, 1
Reference numeral 0 denotes an object to be inspected (object) having a convex central portion, and 11 and 12 are formed so as to be swingable, respectively.
A galvano mirror (optical axis deflection switching means) for deflecting the optical axis 13 in the direction orthogonal to the above, and 14 for the galvano mirror 1
1, 12 and a lens means (first lens means) having a focal length of f1 arranged between the object 10 to be inspected, and DST0 is a distance between the lens means 14 and the central portion of the object 10 to be inspected. . This distance DST0 is variable. 15
Is a galvano control unit (control unit) for controlling the operations of the galvano mirrors 11 and 12 to perform visual field positioning, and 16 is a correction table created from measured data. The galvano control unit 15 is formed so as to perform visual field positioning by adding a value determined by a mathematical formula and a correction table value created from measurement data.

The rough positioning is performed by performing the visual field positioning with a value determined by a mathematical formula, but as it is, it contains an error peculiar to the apparatus, and the visual field positioning to an accurate pattern position cannot be performed. Therefore, the correction table 16 is prepared by measuring a deviation from a reference pattern (not shown) in a state of being roughly positioned in advance.

The principle of focusing the lens means 14 on the entire surface of the object 10 to be inspected by the glass tube according to this embodiment will be described below with reference to the drawings. 2 is a block diagram showing an optical system of one lens means according to an embodiment of the present invention, and FIG. 3 is an enlarged view of FIG.
Is the working distance which is the distance between the work surface of the inspection object 10 and the center of the lens means 14, MD1 is the distance between the rotation center of the galvano mirror 11 or the mirror of the galvano mirror 12 and the center of the lens means 14, and DEFL is the deflection. The quantity, KD1, is the distance between the rotation center of the mirror of the galvanometer mirror 11 or the galvanometer mirror 12 and the camera surface of the optical sensing means 6. It should be noted that the position where this camera surface is placed is the position where the ray passing through the center of the lens means 14 and the lens means 1
It is a position where a light ray passing a distance L0FF1 described later from the center of 4 forms an image.

Further , as shown in FIG. 3, points 0, A, B, B1, C, D, E and G are determined in the XY coordinate system. And
The distance between points DG is L0FF1, and the distance between points A0 is M0F.
The distance between F and the point BD is defined as 11. Furthermore, the angle A
If G0 is defined as α, angle BDE is defined as αf, angle A0C is defined as αm, angle 0BB1 is defined as αk, angle 0DG is defined as αm0, and the angle between the line segment BB1 and the extended battle between line segment EB is defined as β, the following relationship holds and the distance is KD1 is required. That is, α = tan ⁻¹ (DEFL / WD) αf = tan ⁻¹ (L0FF1 / f1 + (DEFL−L0FF1) / WD) αm = (90 ° −α) / 2 αk = 90 ° −αm−αf αm0 = tan ^-1 (MD1 / L0FF1) [beta] = [alpha] m- [alpha] k Further, the following relationships are established from the triangles A0G and B0D. M0FF = MD1 · sin (α) / sin (αm) l1 = (MD1 ² + L0FF1 ² ) ^1/2 · sin (αm0−αm) / sin (180 ° −αk) Furthermore, since the point 0 is the origin, The coordinates of the points A and B1 are shown as follows. A = (M0FF · cos (αm), M0FF · sin (αm)) B1 = (0, l1 · cos (αf) −MD1 + (L0FF1-l1 · sin (αf)) · tan (β))

[0017] Thus, KD1 is expressed by the following equation. KD1 = (M0FF · sin (αm) − (l1 · cos (αf) −MD1 + (L0FF1-l1 · sin (αf)) · tan (β))) / tan (β)

[0018] Next, the operation will be described. First, the object 10 to be inspected is arranged so that the distance between the central portion thereof and the lens means 14 is the distance DST0. Next, the optical axes 13 are switched at high speed by the Galvano mirrors 11 and 12,
Each pattern image on the inspected object 10 is a lens means 14.
The image is photographed by the optical sensitive means 6 such as a TV camera via the, and processed by the processing unit 7. In such a case, by arranging the appropriate lens means 14, it is possible to focus on the entire surface of the inspected object 10 even if the inspected object 10 has a high convex shape in the central portion and a large area due to the paraxial optical characteristics. it can. That is, this utilizes the phenomenon that the focus position becomes farther as the deflection amount DEFL increases. If the height of the object 10 to be inspected is not constant, the magnification of the optical system changes according to the mirror deflection field of view and the size of the pattern changes. Therefore, the processing unit 7 corrects the magnification.

[0019] Then the galvanometer mirrors 11 and 12 swings now to FIG changes in focal position when the deflecting an optical axis 13. FIG. 4 is a graph showing changes in the focal position of an optical system having one lens means according to an embodiment of the present invention. In FIG. 4, the deflection amount DEFL is changed from 0 mm to 120 mm.
Distance KD between the center of mirror rotation and the camera surface by changing to mm
1 is a plot of the difference from the case of DEFL = 0 mm as the camera surface position change amount. In the calculation, the focus position of the lens means 14 is f1 = 225 m.
m, other distances L0FF1 = 10 mm, MD1 =
It was set to 150 mm.

From FIG . 4, it can be seen that the focus position becomes farther as the deflection amount DEFL increases. Therefore, according to the configuration of the first embodiment, by fixing the position of the camera surface of the optical sensitive means 6, it is possible to focus on the object to be inspected 10 having a high convex shape in the central portion, and the entire surface of the object pattern. You can get a high resolution image with. In addition, the movable stage, which has been conventionally required, is no longer necessary, and the entire apparatus can be downsized.

[0021] Example 2. 5 is a block diagram showing the configuration of an image capturing apparatus according to another embodiment of the present invention, FIG. 6 is a block diagram showing the outline of the optical system of FIG. 5, and FIG. 7 is an enlarged view of FIG.
Reference numeral 17 is a lens means (second lens means) having a focal length f2.
Is. That is, in the present embodiment, the camera surface of the optical sensing means 6 and the galvano mirror 1 are added to the configuration of the first embodiment.
The lens means 17 is arranged between the second reflection mirror and the like. In addition, the same reference numerals are given to the corresponding portions shown in the related art and the first embodiment, and the description thereof will be omitted. MD2 is the distance between the rotation center of the galvano mirror 11 or the mirror of the galvano mirror 12 and the center of the lens means 17, KD2
Is the distance between the lens means 17 and the camera surface of the optically sensitive means 6. The position where the camera surface is placed is a position where a light ray passing through the center of the lens means 14 and a light ray passing the distance L0FF1 described above from the center of the lens means 14 form an image through the lens means 17. .

Further , the lens means 14 and the object 10 to be inspected
The distance DST0, which is the distance from the center of the lens, and the focal length f1 are set as follows. That is, when the inspection object 10 has a convex shape with a high central portion, the distance DST0> focal length f
1. D when the inspection object 10 has a low concave shape in the center
When ST0 <f1 and the height of the inspection object 10 is constant, DST0 = f1 is set.

[0023] Hereinafter, the image capturing apparatus according to the present embodiment will be described FIG principle for obtaining a good image resolution on the pattern the entire surface of the inspected object 10. From FIG. 7, the following relationships are established. α = tan ⁻¹ (DEFL / WD) αf = tan ⁻¹ (L0FF1 / f1 + (DEFL−L0FF1) / WD) αm = (90 ° −α) / 2 αk = 90 ° −αm−αf αm0 = tan ⁻¹ (MD1 / L0FF1) β = αm−αk M0FF = MD1 · sin (α) / sin (αm) 11 = (MD1 ² + L0FF1 ² ) ^1/2 · sin (αm0-αm) / sin (180 ° -αk)

Further , as shown in FIGS. 6 and 7, X-Y
Determine points A2 and B2 in the coordinate system. When the Y coordinate of the point B2 is -L0FF2, the point F is a point where the light ray from the point A2 and the light ray from the point B2 form an image, and the angle between the line segment B2F and the X axis is defined as γ, the following relation is obtained. Established, distance KD2
Is required. That is, A2 = (MD2, M0FF · sin (αm)) B2 = (md2, −L0FF2) F = (MD2 + KD2, y) L0FF2 = MD1−11 · cos (αf) − (md2 + 10ff1−11 · sin (αf))・ Tan (β) γ = tan ^-1 (L0FF2 / f2 + tan (β))

[0025] Thus, KD2 is expressed by the following equation. KD2 = (M0FF · sin (αm) −y) · f2 / (M0FF · sin (αm)) = (y + L0FF2) / tan (γ) The Y coordinate of the point F is expressed as follows. y = (f2-L0FF2 / tan (γ)) / (1 / tan (γ) + f2 / (M0FF · sin (αm)))

[0026] Next, the operation will be described. First, the distance between the central portion of the inspection object 10 and the lens means 14 is DST.
It is set to be 0. Next, galvano mirrors 11 and 1
2, the optical axis 13 is switched at high speed, each pattern image on the inspection object 10 is photographed by the optical sensitive means 6 such as a TV camera through the lens means 14 and the lens means 17, and the processing unit 7 It is processed. In such a case, by arranging appropriate lens means 14 and lens means 17, it is possible to focus on the entire surface of the inspected object 10 of various shapes and large areas due to paraxial optical characteristics. That is, when DST0> f1, the deflection amount DEF
As L increases, the focus position becomes far, and DST0 <f1
In this case, the phenomenon that the focus position becomes closer as the deflection amount DEFL increases and the focus position becomes constant in the case of DST0 = f1 is used. The correction operation by the galvano control unit 15 and the processing unit 7 is the same as that in the first embodiment.

[0027] Then the galvanometer mirrors 11 and 12 swings now to FIG changes in focal position when the deflecting an optical axis 13. FIG. 8 is a graph showing the change of the focal position for the optical system of the two lens means according to one embodiment of the present invention. The deflection amount DEFL is changed from 0 mm to 120 mm and the distance KD2 between the lens means 17 and the camera surface is shown. , DEFL = 0 mm is plotted as the amount of change in the camera surface position. The lens means 1
The focal lengths of 4 and 17 are f1 = 450 m, respectively.
m, f2 = 400 mm, L0FF1 for each distance
= 10 mm, MD1 = 150 mm, MD2 = 200 mm
Was calculated as

From this FIG. 8, the working distance W
It can be seen that by setting D, the perspective W control of the focus position can be performed with an increase in the deflection amount DEFL. Therefore, according to the configuration of the second embodiment, by fixing the position of the camera surface of the optical sensitive means 6, the distance D between the lens means 14 and the central portion of the inspected object 10 according to the shape of the inspected object 10.
By setting ST0, it is possible to focus on a large-area object to be inspected of various shapes, and an image with good resolution can be obtained on the entire surface of the object pattern. In addition, the movable stage, which has been required in the past, is unnecessary, and the entire apparatus can be downsized.

[0029] Example 3. In the above description, the two galvanometer mirrors 11 and 12
Although the case where the optical axis is deflected to two axes orthogonal to each other on the inspected object 10 has been described above, one galvanomirror may deflect the optical axis to only one axis. With such a configuration as well, it is possible to obtain a high-resolution image on the entire surface of the object pattern, the movable stage that has been conventionally required is unnecessary, and the entire apparatus can be downsized.

[0030]

As described above, according to the first aspect of the present invention, the first lens means and the optical axis deflection switching means for deflecting the optical axis passing through the first lens means and switching the optical axis at a predetermined frequency are provided. An optical sensitive means which is sensitive to an optical image passing through the optical axis deflection switching means and outputs a predetermined video signal, and an optical axis which is arranged between the optical sensitive means and the optical axis deflection switching means. Second lens means for guiding the optical image passing through the deflection switching means to the optical sensitive means, and a processing unit for processing the video signal output from the optical sensitive means to obtain an image of the object. When the distance between the first lens means and the center of the object is DST0 and the focal length of the first lens means is f1, when the object has a high convex shape in the center, DST0> f1,
If the object has a concave shape with a low central portion, DST0 <
f1, DST0 = f when the height of the object is constant
Since it is configured to be settable as 1, it is possible to reduce the size of the entire apparatus by eliminating the need for a movable stage, and even if it is a large-area object whose height is not constant,
There is an effect that an image of the entire surface of the object pattern can be captured at high speed and with high accuracy.

According to the invention of claim 2, the control unit adds the correction table value that is created from the values as the measurement data determined by the formula, performs the viewing position by controlling the optical axis deflection switching means Since it was configured to prepare,
There is an effect that the object pattern image with higher accuracy than that of the invention of claim 1 can be captured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image capturing device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an optical system having one lens means according to an embodiment of the present invention.

FIG. 3 is an enlarged view of FIG.

FIG. 4 is a graph showing a change in focal position for an optical system having one lens means according to an embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an image capturing device according to another embodiment of the present invention.

FIG. 6 is a block diagram showing an outline of the optical system of FIG.

FIG. 7 is an enlarged view of FIG.

FIG. 8 is a graph showing a change in focal position for an optical system having two lens means according to an embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a conventional image capturing device.

[Explanation of symbols]

6 Optical Sensing Means, 7 Processing Unit, 10 Object to be Inspected (Object), 11 and 12 Galvano Mirror (Optical Axis Deflection Switching Means), 13 Optical Axis, 14 Lens Means (First Lens Means), DST0 Distance , 15 Galvano control unit (control unit), 16 Correction table, 1
7 Lens means (second lens means).

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-193677 (JP, A) JP-A-1-135273 (JP, A) JP-A-6-202023 (JP, A) Actual Kaihei 5- 33109 (JP, U) Japanese Patent Publication No. 9-509256 (JP, A) US Pat. No. 5192980 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11 / 00-11 / 30 G01N 21/956

Claims (2)

(57) [Claims] 1. A first lens means for obtaining an optical image of an object, an optical axis deflection switching means for deflecting an optical axis passing through the first lens means and switching at a predetermined frequency, and the optical axis deflection switching. An optical image sensing device which outputs a predetermined image signal in response to an optical image passing through the image sensing device, and an optical axis deflection switching device which is arranged between the optical axis deflection switching device and the optical sensing device. A second lens means for guiding an optical image to the optical sensitive means; and a processing unit for processing the video signal output from the optical sensitive means to obtain an image of the object, If the distance between one lens means and the center of the object is DST0 and the focal length of the first lens means is f1, then DST0> f1 if the object has a highly convex center, and If the object has a low concave shape in the center When the height of the object is constant, DST0 <f1 is set, and DST0 = f1 is set so that the image can be set. 2. A control unit for adding a value determined by a mathematical expression and a correction table value created by measurement data to control the optical axis deflection switching means to perform visual field positioning. The image capturing device according to claim 1.